Omron C500-LDP01-V1, Operation Manual

Page: 31 / 59

$
Pin 2 ON (WRIT(87)/READ(88) Operation)
Data is transferred to and from the PC using the I/O WRITE/READ
(WRIT(87)/READ(88)) instructions.
Pin 2 OFF (Normal I/O Operation)
Data is transferred to and from the PC through 2 words allocated for I/O.
Process Content Time requirements
Overseeing Watchdog timer set; indicators set, etc. 177 s
Program
execution Program executed. Total execution time for all
instructions varies with pro-
gram size, the instructions
used, and execution condi-
tions. Refer to
Instruction
Execution Times for details.
I/O refresh Pin 2 ON Pin 2 OFF Varies with the method of
data transfer to/from the PC.
Input refresh
WRIT(87)
execution (see
Note 2 below)
Clock read/store
READ(88)
execution (see
Note 2 below)
Output refresh Input refresh
Clock read/store
Output refresh Input refresh: 47.50 s
WRIT(87): 1.361 ms
Clock read/store: 192.50 s
READ(88): 753.75 s
Output refresh: 35.00 s
Scan time = Overseeing time + Program execution time + I/O refresh time
Note 1. The method of data transfer between the Unit and the PC is determined by
the setting of pin 2 of the back panel DIP switch.
The scan time is longer when pin 2 is ON, because of the time required to
execute WRIT(87) and READ(88), but these instructions allow a large
amount of data to be transferred all at once.
2. When WRIT(87) is executed during the I/O refresh, the data written from the
PC is stored in DM 064 through DM 095 in the Unit.
When READ(88) is executed, the data stored in DM 096 through DM 127 in
the Unit is transferred to the PC.
3. The processing times given for the execution of WRIT(87) and READ(88)
are the times required for the transfer of the maximum 32 words of data.
Long Scan Times
Scan time (ms) Possible adverse affects
10 or greater TIMH(15) inaccurate
100 or greater A watchdog timer error occurs, operation stops, and the Unit
is automatically switched to PROGRAM mode.
Note If the scan time exceeds 100 ms, operation of the Unit is stopped and the Unit is
automatically switched to PROGRAM mode. It is necessary to recheck the pro-
gram at this point.
5-3 Instruction Execution Times
This following table lists the execution times for all instructions that are available
for the Ladder Program I/O Unit. The maximum and minimum execution times
and the conditions which cause them are given where relevant. When “word” is
referred to in the Conditions column, it implies the content of PC I/O bits, external
I/O bits, or work bits.
" *+ )
Section 5-3